Serum cholesterol has been implicated in connection with atherosclerosis, a form of heart disease. Efforts have therefore been made to lower serum cholesterol. One approach is to alter the diet by reducing cholesterol intake.
A source of dietary cholesterol is chicken eggs. For example, a "large" chicken egg contains on the average 213 milligrams of total cholesterol. Completely eliminating egg product intake would adversely affect many standard food recipes. While egg substitutes are lower in cholesterol, they are usually poor imitations of real eggs from a texture and taste standpoint. They also often differ in other characteristics that are important to consumers. In this regard, egg substitutes often either contain no egg yolks, or they contain egg yolks that have been treated in ways that are detrimental.
Another concern is the embarrassment factor for those who use egg substitutes. When purchasing or using such specialty dietary products there is a risk that private medical conditions will become public knowledge.
Efforts have therefore been made to try to reduce the cholesterol levels in the eggs themselves. One approach is by controlling the diet of chickens by using low fat, high fiber diets, and by reducing the stress levels for chickens (e.g. using reduced and/or red lights; providing a clean environment; reducing the number of chickens per cage). At best, this has lead to "large" eggs which average (in a randomly selected test sample) above 165 mg per 50 g of egg white and yolk.
U.S. regulatory authorities have promulgated rules that will prohibit advertisement of reduced cholesterol levels in foods unless there is at least a twenty-five percent reduction from "normal" levels. Thus, "large" eggs having (on average) 160 mg or less total cholesterol per 50 g of egg white and yolk are highly desired. "Total cholesterol" can be determined using procedures based on M. Adams et al., 69 J. Assoc. Off. Anal. Chem. 844-846 (1986). See also Official Methods Of Analysis (1990), 15th Edition, Method 976.26 AOAC Arlington, Va. The disclosure of these publications, and of all the other publications referred to herein, are incorporated by reference as if fully set forth herein.
There have been attempts to reduce the cholesterol content of eggs using drugs. In fact, sterols and triparanol have achieved greater than 25% reductions in chicken eggs. However, these drugs are not on the GRAS (generally recognized as safe) listing. Thus, their use would cause adverse labeling and sales restrictions, and there may well be safety problems associated with their use.
Candling is a known technique of shining a light through an egg in order to spot cracks or blood spots by viewing the shadow. It has been reported that candling techniques are now being used with computer imaging systems so as to automate defect spotting. See Poultry Times, p. 6, (Mar. 1, 1993). However, the art has not applied candling techniques to assist in selecting low cholesterol eggs.
The need therefore still exists to achieve a 25% or more reduction in total cholesterol in chicken eggs using techniques that do not require the use of sterols, triparanol, or other drugs that are not on the GRAS list.